1. Field of the Invention
The present invention relates to a toner discharging device and a toner cartridge. More particularly, the present invention relates to a toner discharging device and a toner cartridge to be used in an image forming apparatus that performs image formation with the use of a two-component developer including a toner and a magnetic carrier.
2. Description of the Related Art
In a conventional developing device for containing and supplying, to a photoconductor drum, a two-component developer including a toner and a magnetic carrier, toner is supplied from a toner cartridge to the developing device when the toner in the developing device runs low due to consumption by image formation and the toner concentration in the two-component developer is detected to be lower than a specified value.
For example, there has been used a developer supplying container comprising: a main body for containing a developer; a supply port provided in the bottom of the main body for supplying the developer; a conveyance path for conveying the developer toward the supply port; and a conveyance screw provided in the conveyance path, the conveyance screw including a screw axis and a spiral fin, wherein the conveyance screw is rotated about the screw axis thereby to convey the developer toward the supply port and supply the developer to a developing device through the supply port (see Japanese Unexamined Patent Application Publication No. 2011-033706).
Japanese Unexamined Patent Application Publication No. 2011-033706 discloses an embodiment in which the conveyance screw has a first region located just before the supply port and a second region located at an upstream side relative to the first region, the diameter of the spiral fin in the first region is smaller than the diameter of the spiral fin in the second region, and the conveyance screw further includes, at a position adjoining the spiral fin in the first region and facing the supply port, a protruding spatula extending in the axial direction of the screw axis.
In the developer supplying container disclosed in Japanese Unexamined Patent Application Publication No. 2011-033706, the conveyance screw has the two regions different in the diameter of the spiral fin and includes a protruding spatula near the supply port so that the toner conveyance ability in the first region just before the supply port is less than the toner conveyance ability in the second region, and therefore the supply is not decreased to ensure a predetermined supply.
However, in conventional toner supplying devices and the supplying container disclosed in Japanese Unexamined Patent Application Publication No. 2011-033706, the toner staying around the supply port for discharging the toner to an exterior collides with the toner conveyed thereto through the conveyance path, and some toner is compressed and aggregated there, having nowhere else to go.
In particular, when having been transported over a long distance or having been left over a long period of time under a high-temperature environment and therefore having a reduced flowability, the toner cannot be discharged from the supply port smoothly to raise the probability that the toner is compressed and aggregated there.